Counterbalanced fire-shutter



W. B. GERVAIS.

COUNTERBALANCED FIRE SHUTTER.

APPLICATION FILED AUG.20, 1917.

Patented Sept. 21,1920.

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- UNITED STATESIPATTENT OFFICE. s

' wnnvwnrGnu: erg-savers, or cnrcee InnInors, ASSIGNQR TO VARIETY MANUF C- TUBING COMPANY, or CHICAGO, ILLINOIS, A CORPORATION or LLINO S.

OOUN'IERBALANCED FIRE-SHUTTER.

' Specification'of Letters Patent.

Pet l te S pt. 192 0 Application filed au usmo, 1917. :Seria1 No, 187,130.

I 7" 0 all whom itmag concern; I I

Be it known that I, WAINWRIGHT B. GER- vars, a citizen of the United. States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented a certain Counterbalanced Fire-Shutters, of which'the following is a full, clear, concise, and exact description, reference being had to the accompanymg drawings, forming part of this specificatron. 1

.My invention relatesto counter-balanced lire shutters.

Heretofore it has been customary to counter-balance a rolling fire shutter wlth a coil spring mounted in the drum of the shutter. Such manner of counter-balancing the shutter has a number of disadvantages; It is difficult to construct a counter-balancing spring which will'follow the law of actionof the rolling shutter and will counter-balance the weight of the same throughout the;entire travel. It is a familiar fact that. 1n the sprzngbalanced rollmgshutters the sprmg will counter-balance theshutter when it is up-or when itis down but that in the middle part of the movement of the shutter the curtain is not properly counter-balanced.

The spring after itis once installed in the drum is difficult. to manipulate The strength and resiliency of spring made even under identical conditions are variable.

According tomy invention springs are entirely dispensed with and the curtain is exactly counter-balanced at every position or condition. Consequently the curtain may be moved with aminimum of effort. The counter-balancing mechanism which I employ is of the type which will cause the shutter to close automatically if the operating parts of the counter-balancing mechanism are broken or'become unfastened.

I shall now describe a particular embodiment of my invention to teach those skilled in the art how to practice the same.

In the accompanying drawings which form a part of the present specification Figure 1 is a front elevational view of a device embodying my invention;

Fig. 2 is a section taken on the line 2-2 link 14 or destruction of the cable 11, the

of Fig. 1; and I Fig. 3 is an end elevational view of the same.

The rolling shutter 1 consists-of a plurality of metal flaps hinged together and secured atthe inner endto adrum, notshown,

which drum is fastened to the shaft 2. The

shaft-of the; drum has bearings in the heads '3 and 4:Of the generally, cylindrical casing 5. .;,The lower end of the shutter 1 is provided with the flanges 6, preferably formed of angle iron. The bottom: flanges of theiangle iron'6 are cut away andthe edges of the curtain 1 run'in suitable guidesf? upon each side of the door. These guides 7 preferably form ,continuations of the heads 3,.ajnd 4 of the casing .5 as is understoo'd in. the art. Suitable handles 8 are fastened on the end of the curtain 1 for operatingthe same.

The law of. operation of the shutters is as follows:

When the shutter is extended to the bottom then the weight W'of the shutter operates with a certain lever arm r. When the shutter is rolled up on the drum the diameter of the drum has been-increased by the amount-of curtain rolled thereupon so that the. radius has changed'to R. The weight which operates to unbalance the curtain has been decreased by the amount which has been rolled uponthe drum sothat the weight may now be represented by w, consequently the turning efi'ect upon-the'drummaybe represented when the curtain is down by the quantity Wfr. .VVhen the shutter is rolled to .1178 open position the forceacting to unbalance the shutter may be represented by the quantity 'w R. v p

Inasmuch as the curtain rolls up gradually and consequently loses weight gradually and the drum diameter increases gradually, it can be seen that a straight line law governs the unbalanced condition of the shutter.

In order to properly counter-balance this condition a counter-balancing device having a similar straight line law of action is provided in the spiral pulley 9 and weight 10. The cable 11 is fastened to the pulley 9 and the weight 10 lies in a bight of the cable 11, the upper end of the cable being attached to a suitable support. The support which I have illustrated comprises a hook 12 pivoted at 13 and held against movement by a fusible link 14.

In the event of destruction of the fusible weight 11 would be taken ofl ofthe cable,

thus removing the counter-balancing influence and permitting the curtain 1 todrop.

It is to be understood that when the ourbe geared thereto.

tain is rolled up the unbalancing force. ofv the curtain is less than when the curtain has been, unrolled. The weight 10 operates on a shorter radius arm than when the curtain is unrolled. Consequently a very nice counter-balance is secured at all times. 7 While I have described the counter-balanceas operating onja straight line law of action, it is to be understood that theweight and pulley 10, 9 may be made to compensate for-any type of unbalanced load bycausing the groove in the pulley 9 to follow the 'desired variation. It is further to be understood that in practice the weight 10 is provided with a well or chute and that the pulley '9, instead of being connected directly to the shaft Qand the drum of the curtain,'may I do not intend to be limited'to the precise'details shown and'described.

1. In combination, a rolling shutter norm'a'll'y unbalanced by the unrolled portion of the s hu'tterfa shaft operatively secured to said 'shutter,"a spiral pulley connected to said shaft, a cable or the like secured 'to'the spiral pulleyfa'nd wrapped thereupon, a vi eiglit sli'dabl'y resting in' a bight of said cable and fusible means anchoring the free end of the cable.

my name this 1917.

to said. shutter, a pulley having a spiral groove connected'to said shaft, a cable or the like in said spiral groove, a counterbalancing weight on said cable, thermally releasable means holding the cable, said coun-' terbalancing weight setting up a turning moment on said shaft varying with the varying positions of the door to counterbalance the same in the normal operation thereof, said cable being adapted to release the counterbalancing influence of said c0unte'rbalanc'ing weight upon destruction of said thermally releasable means.

4. In combination, a rolling shutter nor- 7 mally unba'lanced'by the unrolled portion of the shutter, a shaft operatively secured to said shutter, a spiral pulley connected to said shaft, a cable or the like secured to the spiral pulley and wrapped thereupon, a

weight suspended by -a bight in the cable,

fusible means anchoring the free end 0mm cable, saidcable being adapted to release the weight upon destruction of said fusible means.

5. In combination, a shaft, a rolling shutter "operatively secured thereto, vertically arranged guide means for guiding said shutter in its 'vertlcal movement, a counterbalfancing weight setting up a turning momento'n's'aiol shaft varying with the varying vertical positions of said rolling shutter to effectively counterbalance the same throughout the various positions along said vertically arrangedguide 'means and thermally controlled means for releasing the counterbalaneinginfiuence of said counterbalancing weight, permitting the door to close unimpeded bythe action of said counterweight.

In witness whereof, I hereunto subscribe 16th day of August, A. D.

IWAIVNWRIGHT B. enRvAis. 

